Graphical user interface for a display screen or portion thereof



FIG. 1 is a front view of a graphical user interface for a display screen or portion thereof showing our new design; and,

FIG. 2 is a front view of a second embodiment thereof.

The broken line showing of the display screen or portion thereof forms no part of the claimed design. 

The ornamental design for a graphical user interface for a display screen or a portion thereof, as shown and described. 